DOCSLIB.ORG

QUALITY of WATER COLORADO RIVER BASIN Progress Report No. 22

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
QUALITY of WATER COLORADO RIVER BASIN Progress Report No. 22 QUALITY OF WATER COLORADO RIVER BASIN Progress Report No. 22 U.S. Department of the Interior Bureau of Reclamation Upper Colorado Region 2005 2 TABLE OF CONTENTS SUMMARY ...................................................................................................................................... 1 CHAPTER 1 - INTRODUCTION ..................................................................................................... 3 AUTHORIZATION FOR REPORT ............................................................................................ 3 LEGAL ASPECTS ...................................................................................................................... 4 Water Quantity ................................................................................................................... 4 Water Quality ..................................................................................................................... 5 CHAPTER 2 – SALINITY CONDITIONS ........................................................................................ 7 CAUSES OF SALINITY .............................................................................................................. 7 HISTORIC SALINITY CONDITIONS .......................................................................................... 9 FACTORS INFLUENCING SALINITY......................................................................................... 9 Streamflow ……………………………………..………………………………………………... 9 Reservoir Storage ……………………………………………………………………………... 10 Reservoir Initial Filling Salt Leaching Impacts to Salinity ................................................. 11 SALINITY TREND STUDIES .................................................................................................... 14 NATURAL VARIATION IN SALINITY ....................................................................................... 16 AGRICULTURAL SOURCES OF SALINITY ............................................................................ 16 UPPER BASIN IRRIGATION.................................................................................................... 17 WATER USE BY AGRICULTURE & MUNICIPAL & INDUSTRIAL USERS............................. 17 FUTURE WATER DEVELOPMENT ......................................................................................... 18 COMPLIANCE WITH THE SALINITY STANDARDS................................................................ 21 SALINITY CONTROL................................................................................................................ 22 CHAPTER 3 - SALINITY MODELING ......................................................................................... 23 ECONOMIC SALINITY DAMAGE MODEL .............................................................................. .23 COLORADO RIVER SIMULATION SYSTEM .......................................................................... 24 Salinity Model Verification .............................................................................................. .24 Future Salinity Projections ............................................................................................... 24 CE-QUAL-W2 RESERVOIR MODELING ................................................................................. 26 Model Calibration ............................................................................................................. 27 Future Salinity Scenarios ................................................................................................. 27 CHAPTER 4 - TITLE I SALINITY CONTROL PROGRAM ………………………………………….33 COACHELLA CANAL LINING .................................................................................................. 33 PROTECTIVE AND REGULATORY PUMPING....................................................................... 34 YUMA DESALTING PLANT...................................................................................................... 35 WELLTON-MOHAWK IRRIGATION AND DRAINAGE DISTRICT........................................... 36 Acreage Reduction .......................................................................................................... 37 District Irrigation Efficiency Improvement Program ......................................................... 37 TABLE OF CONTENTS (Continued) On-Farm Improvements Program ................................................................................... 37 Irrigation Management Services Program ....................................................................... 37 Research and Demonstration Program ........................................................................... 38 Education and Infomation Program ................................................................................. 38 Results ............................................................................................................................. 38 Status ............................................................................................................................... 38 CHAPTER 5 - TITLE II SALINITY CONTROL PROGRAM ......................................................... 41 USDA / NRCS .......................................................................................................................... 41 BLM .......................................................................................................................................... 42 Planning and Public Involvement .................................................................................... 42 Nonpoint Source Control ................................................................................................. 43 Point Source Control ....................................................................................................... 43 Estimating Salinity Control ............................................................................................... 44 RECLAMATION ........................................................................................................................ 44 Background ...................................................................................................................... 44 Public Review .................................................................................................................. 45 Guidelines ........................................................................................................................ 46 Performance Review ....................................................................................................... 46 CHAPTER 6 - OTHER WATER QUALITY ISSUES .................................................................... 49 PERCHLORATE ....................................................................................................................... 49 THM........................................................................................................................................... 49 ALGAE....................................................................................................................................... 49 TMDL's. ..................................................................................................................................... 50 URANIUM MINE TAILINGS. ................................................................................................... 51 REFERENCES CITED ................................................................................................................. 53 GENERAL REFERENCES ........................................................................................................... 56 APPENDIX A – SALINITY DATA .....................................................................................................63 ii TABLES Table 1 – Quantified Sources of Salt Loading ................................................................................ 8 Table 2 - Hydrology and Salt at Grand Canyon and Virgin River Streamflow Gages................... 12 Table 3 - Upper Basin Depletion Projections ............................................................................... 19 Table 4 - Lower Basin Depletion Projections ............................................................................... 20 Table 5 - Salinity Control Requirements and Needs .................................................................... 22 Table 6 - Probability of Exceeding Numeric Criteria ..................................................................... 26 Table 7 - Hydrology of the Individual Years Modeled and Percentage of Long Term Averages either 1964-2002 or 1992-2002) ................................................................................... 28 Table 8 - Statistical Hydrology for each trace arraying potential future salinity ranges below Glen Canyon and Hoover Dams .................................................................................. 30 Table 9 - District Pumped Drainage Return Flow ......................................................................... 39 Table 10 - USDA Salinity Control Program Summary .................................................................. 41 Table 11 - Estimated Salt Retained on BLM Lands ..................................................................... 44 Table 12 - Reclamation Basinwide Salinity Control Program Salt Controlled, tons/yr ................. 48 FIGURES Figure 1 - Sources of Salinity ........................................................................................................
Load more

Recommended publications
  • The Little Colorado River Project: Is New Hydropower Development the Key to a Renewable Energy Future, Or the Vestige of a Failed Past?
    COLORADO NATURAL RESOURCES, ENERGY & ENVIRONMENTAL LAW REVIEW The Little Colorado River Project: Is New Hydropower Development the Key to a Renewable Energy Future, or the Vestige oF a Failed Past? Liam Patton* Table of Contents INTRODUCTION ........................................................................................ 42 I. THE EVOLUTION OF HYDROPOWER ON THE COLORADO PLATEAU ..... 45 A. Hydropower and the Development of Pumped Storage .......... 45 B. History of Dam ConstruCtion on the Plateau ........................... 48 C. Shipping ResourCes Off the Plateau: Phoenix as an Example 50 D. Modern PoliCies for Dam and Hydropower ConstruCtion ...... 52 E. The Result of Renewed Federal Support for Dams ................. 53 II. HYDROPOWER AS AN ALLY IN THE SHIFT TO CLEAN POWER ............ 54 A. Coal Generation and the Harms of the “Big Buildup” ............ 54 B. DeCommissioning Coal and the Shift to Renewable Energy ... 55 C. The LCR ProjeCt and “Clean” Pumped Hydropower .............. 56 * J.D. Candidate, 2021, University oF Colorado Law School. This Note is adapted From a final paper written for the Advanced Natural Resources Law Seminar. Thank you to the Colorado Natural Resources, Energy & Environmental Law Review staFF For all their advice and assistance in preparing this Note For publication. An additional thanks to ProFessor KrakoFF For her teachings on the economic, environmental, and Indigenous histories of the Colorado Plateau and For her invaluable guidance throughout the writing process. I am grateFul to share my Note with the community and owe it all to my professors and classmates at Colorado Law. COLORADO NATURAL RESOURCES, ENERGY & ENVIRONMENTAL LAW REVIEW 42 Colo. Nat. Resources, Energy & Envtl. L. Rev. [Vol. 32:1 III. ENVIRONMENTAL IMPACTS OF PLATEAU HYDROPOWER ...............
    [Show full text]
  • Imperial Dam/All American Canal Projects Update-2021
    Imperial Dam/All American Canal Projects Update-2021 David Escobar General Superintendent, Operations & Maintenance AAC/River Division May 19, 2021 www.iid.com www.iid.com 2 www.iid.com 3 Executive Summary • Imperial Dam is primarily a concrete slab and buttress structure on the Colorado River located approximately 18 northeast of Yuma, Arizona. The Dam was constructed between 1936 and 1938 by Reclamation to impound water for irrigation. • The Dam’s overall length is approximately 3,479 feet. The sections of the Dam consist of the California abutment, the All American Canal (AAC) Headworks, the California Sluiceway, the overflow weir (spillway) section, the Gila Canal Headworks, and the Arizona abutment. www.iid.com 4 Projects List • Imperial Dam Roller Gates 1 through 4 Overhaul completed in 2018, total project cost-$2,955,900 • Imperial and Laguna Dams Electrical Upgrade Project completed in 2018, total project cost-$20,940,977 • Imperial Dam Sluiceway Gate Replacement Project completed in 2019, total project cost-$3,132,200 • Imperial Dam Concrete Repairs 2019, total project costs- $823,954 www.iid.com 5 Projects List • Imperial Dam Desilting Basin Clarifier Valve Replacement Project will be completed in 2021, total project cost- $1,985,200 • Senator Wash Units 1, through 6 Rewind Stator and Pump Refurbishment 2019-2021, total project cost-$2,145,800 • Gila Headworks Trunnion Repair Project 2021-2022, estimated project costs-$4,156,635 • Gila Headworks Gate Replacement 2021-2022, estimated project costs-$2,900,000 www.iid.com 6 Projects List • Pilot Knob Wasteway/Spill Gate Replacement Project will be completed in 2021, project costs-$1,861,600 • Imperial Dam Desilting Basins Sludge Pipe Replacement Project 2022, estimated project costs-$15,000,000 • Gila Gravity Main Canal Unused Radial Gates Permanent Closure Project 2022, estimated project costs-$2,900,000 www.iid.com 7 Questions? www.iid.com.
    [Show full text]
  • Saline Soils and Water Quality in the Colorado River Basin: Natural and Anthropogenic Causes Gabriel Lahue River Ecogeomorphology Winter 2017
    Saline soils and water quality in the Colorado River Basin: Natural and anthropogenic causes Gabriel LaHue River Ecogeomorphology Winter 2017 Outline I. Introduction II. Natural sources of salinity and the geology of the Colorado River Basin IIIA. Anthropogenic contributions to salinity – Agriculture IIIB. Anthropogenic contributions to salinity – Other anthropogenic sources IV. Moving forward – Efforts to decrease salinity V. Summary and conclusions Abstract Salinity is arguably the biggest water quality challenge facing the Colorado River, with estimated damages up to $750 million. The salinity of the river has doubled from pre-dam levels, mostly due to irrigation and reservoir evaporation. Natural salinity sources – saline springs, eroding salt-laden geologic formations, and runoff – still account for about half of the salt loading to the river. Consumptive water use for agricultural irrigation concentrates the naturally- occurring salts in the Colorado River water, these salts are leached from the root zone to maintain crop productivity, and the salts reenter the river as agricultural drainage water. Reservoir evaporation represents a much smaller cause of river salinity and most programs to reduce the salinity of the Colorado River have focused on agriculture; these include the lining of irrigation canals, irrigation efficiency improvements, and removing areas with poor drainage from production. Salt loading to the Colorado River has been reduced because of these efforts, but more work will be required to meet salinity reduction targets. Introduction The Colorado River is one of the most important rivers in the Western United States: it provides water for approximately 40 million people and irrigation water for 5.5 million acres of land, both inside and outside the Colorado River Basin (CRBSCF, 2014).
    [Show full text]
  • Arizona Fishing Regulations 3 Fishing License Fees Getting Started
    2019 & 2020 Fishing Regulations for your boat for your boat See how much you could savegeico.com on boat | 1-800-865-4846insurance. | Local Offi ce geico.com | 1-800-865-4846 | Local Offi ce See how much you could save on boat insurance. Some discounts, coverages, payment plans and features are not available in all states or all GEICO companies. Boat and PWC coverages are underwritten by GEICO Marine Insurance Company. GEICO is a registered service mark of Government Employees Insurance Company, Washington, D.C. 20076; a Berkshire Hathaway Inc. subsidiary. TowBoatU.S. is the preferred towing service provider for GEICO Marine Insurance. The GEICO Gecko Image © 1999-2017. © 2017 GEICO AdPages2019.indd 2 12/4/2018 1:14:48 PM AdPages2019.indd 3 12/4/2018 1:17:19 PM Table of Contents Getting Started License Information and Fees ..........................................3 Douglas A. Ducey Governor Regulation Changes ...........................................................4 ARIZONA GAME AND FISH COMMISSION How to Use This Booklet ...................................................5 JAMES S. ZIELER, CHAIR — St. Johns ERIC S. SPARKS — Tucson General Statewide Fishing Regulations KURT R. DAVIS — Phoenix LELAND S. “BILL” BRAKE — Elgin Bag and Possession Limits ................................................6 JAMES R. AMMONS — Yuma Statewide Fishing Regulations ..........................................7 ARIZONA GAME AND FISH DEPARTMENT Common Violations ...........................................................8 5000 W. Carefree Highway Live Baitfish
    [Show full text]
  • West Colorado River Plan
    Section 9 - West Colorado River Basin Water Planning and Development 9.1 Introduction 9-1 9.2 Background 9-1 9.3 Water Resources Problems 9-7 9.4 Water Resources Demands and Needs 9-7 9.5 Water Development and Management Alternatives 9-13 9.6 Projected Water Depletions 9-18 9.7 Policy Issues and Recommendations 9-19 Figures 9-1 Price-San Rafael Salinity Control Project Map 9-6 9-2 Wilderness Lands 9-11 9-3 Potential Reservoir Sites 9-16 9-4 Gunnison Butte Mutual Irrigation Project 9-20 9-5 Bryce Valley 9-22 Tables 9-1 Board of Water Resources Development Projects 9-3 9-2 Salinity Control Project Approved Costs 9-7 9-3 Wilderness Lands 9-8 9-4 Current and Projected Culinary Water Use 9-12 9-5 Current and Projected Secondary Water Use 9-12 9-6 Current and Projected Agricultural Water Use 9-13 9-7 Summary of Current and Projected Water Demands 9-14 9-8 Historical Reservoir Site Investigations 9-17 Section 9 West Colorado River Basin - Utah State Water Plan Water Planning and Development 9.1 Introduction The coordination and cooperation of all This section describes the major existing water development projects and proposed water planning water-related government agencies, and development activities in the West Colorado local organizations and individual River Basin. The existing water supplies are vital to water users will be required as the the existence of the local communities while also basin tries to meet its future water providing aesthetic and environmental values.
    [Show full text]
  • November 17, 2017 David Beaver & Karen Summitt 8226 S Evergreen Dr Mohave Valley, AZ 86440 Re: Purchase and Sale Agreement F
    From: Karen Summitt To: Thomas Buschatzke; Sharon Scantlebury Subject: Fw: Objections to the MVIDD Water Transfer Date: Thursday, November 16, 2017 6:24:42 PM Attachments: ADWR Letter.docx November 17, 2017 David Beaver & Karen Summitt 8226 S Evergreen Dr Mohave Valley, AZ 86440 Re: Purchase and Sale Agreement for CAWCD to Acquire Water Rights and Land in Mohave Valley Irrigation and Drainage District, Mohave County, Arizona Dear Thomas Buschatzkle, I write to advise you that I am opposed to the proposed Central Arizona Water Conservation District (CAWCD) land and water purchase to move Colorado River water, prudently set aside for rural Arizona Colorado River mainstream users, to central Arizona for replenishment. As you may recall, the Mohave County Board of Supervisors passed two resolutions opposing the permanent transfer of any Colorado River Water Rights and Allocations to the Central Arizona Water Conservation District for use in the Central Arizona Groundwater Replenishment District – first as to the Quartzsite transfer and second as to the WPI-WAN transfer in the Mohave Valley Irrigation and Drainage District. Here is why I oppose this purchase and transfer of our water: First, as a matter of public policy, 4th Priority Colorado River water allocated to the users on the mainstream of the River, such as Mohave Valley Irrigation and Drainage District (“MVIDD”) in this case, should not be transferred away from mainstream of the River. This is part of the water that the State of Arizona requested be reserved for municipal and industrial uses along the River. Except for that small reservation of 4th Priority Colorado River water to the users on the mainstream, CAWCD received all of Arizona’s Colorado River entitlement remaining at the time that CAWCD and the United States entered into their initial agreement in 1972.
    [Show full text]
  • Floating the Dirty Devil River
    The best water levels and time Wilderness Study Areas (WSA) of year to float the Dirty Devil The Dirty Devil River corridor travels through two The biggest dilemma one faces when planning BLM Wilderness Study Areas, the Dirty Devil KNOW a float trip down the Dirty Devil is timing a WSA and the Fiddler Butte WSA. These WSA’s trip when flows are sufficient for floating. On have been designated as such to preserve their wil- BEFORE average, March and April are the only months derness characteristics including naturalness, soli- YOU GO: that the river is potentially floatable. Most tude, and primitive recreation. Please recreate in a people do it in May or June because of warm- manner that retains these characteristics. Floating the ing temperatures. It is recommended to use a hard walled or inflatable kayak when flows Dirty Devil are 100 cfs or higher. It can be done with “Leave-no-Trace” River flows as low as 65 cfs if you are willing to Proper outdoor ethics are expected of all visitors. drag your boat for the first few days. Motor- These include using a portable toilet when camping ized crafts are not allowed on this stretch of near a vehicle, using designated campgrounds The name "Dirty Devil" tells it river. when available, removing or burying human waste all. John Wesley Powell passed in the back country, carrying out toilet paper, using by the mouth of this stream on Another essential consideration for all visitors camp stoves in the backcountry, never cutting or his historic exploration of the is flash flood potential.
    [Show full text]
  • Preliminary Report on Some Uranium Deposits Along the West Side of the San Rafael Swell, Emery County, Utah
    UNITED STATES ATOMIC ENERGY COMMISSION RMO-673 PRELIMINARY REPORT ON SOME URANIUM DEPOSITS ALONG THE WEST SIDE OF THE SAN RAFAEL SWELL, EMERY COUNTY, UTAH By Millard L. Reyner October 1950 SI-7c1 Division of Raw Materials Exploration Branch Technical Information Service, Oak Ridge, T•nn•ss•• ; "N_ ' \ - —rrs1 • „ 6 NOV 1952 METALLURGY AND CERAMICS Reproduced direct from copy a3 submitted to this office. AEC,Oak Ridge,Tenn.,8-13-51--515-W5593 CONTMITS Page Introduction 1 Geography 3 History 4 Regional geology 4 Economic geology 5 General 5 Mineralogy 7 Deposits examined 8 Lone Tree group. 8 Hard Pan group 11 Dalton group 12 Dexter group 12 Clifford Smith claim 16 Wickiup group 17 Gardell Snow's claim 20 Dolly group 20 South Fork group 20 Hertz No. 1 claim 21 Pay Day claim. Green Vein group. and Brown Throne group 21 Dirty Devil group 26 Summary and conclusions 30 iii ILLUSTRATIONS Page Figure 1. Index Map of Utah showing location of area examined. • •••••••• OOOOO ••. 2 Figure 2. Map showing locations of uranium prospects and samples on a mesa 4 miles southwest of the San Rafael River bridge. OOOOO . 9 Figure 3. Sketch showing plan, sections, and samples of the Lone Tree adit .••••• OOOOO 10 Figure 4. Plan and sections of Dalton Group showing sample locations and assays . 13 Figure 5. Plan of adit on Dexter Group showing sample looations and assays. 15 Figure 6. Sketch of Block Mountain showing locations of samples in Wickiup Group•• OOOOOO 18 Figure 7. Sketch showing sample locations and assays in main workings of Wickiup Group on the west side of Block Mountain.
    [Show full text]
  • The Yuma Project on Uninsured Children
    The Yuma Project On Uninsured Children William G. Johnson, Ph.D. Saundra E. Johnson, M.P.A. Steven C. Marcus, Ph.D. Amy Bartels, M.Ph. Ann G. Lawthers, Sc.D. December 2001 The Yuma Project on Uninsured Children is a project of the School of Health and Administration & Policy, College of Business, Arizona State University, supported and coordinated by the Flinn Foundation Table of Contents Research Project Staff..........................................................................................iii Acknowledgements...............................................................................................v Advisory Committee............................................................................................vii 1. Introduction..................................................................................................1 A Profile of Yuma County and its Children ..........................................2 The CHDS Data Set...............................................................................4 2. Creating a Community Data Set Focused on Children: Yuma’s Community Health Data System....................................................5 The Process............................................................................................5 The Method............................................................................................6 The Data................................................................................................ 7 3. Estimating the Number of Uninsured Children ..........................................11
    [Show full text]
  • Management of the Colorado River: Water Allocations, Drought, and the Federal Role
    Management of the Colorado River: Water Allocations, Drought, and the Federal Role Updated March 21, 2019 Congressional Research Service https://crsreports.congress.gov R45546 SUMMARY R45546 Management of the Colorado River: Water March 21, 2019 Allocation, Drought, and the Federal Role Charles V. Stern The Colorado River Basin covers more than 246,000 square miles in seven U.S. states Specialist in Natural (Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada, and California) and Resources Policy Mexico. Pursuant to federal law, the Bureau of Reclamation (part of the Department of the Interior) manages much of the basin’s water supplies. Colorado River water is used Pervaze A. Sheikh primarily for agricultural irrigation and municipal and industrial (M&I) uses, but it also Specialist in Natural is important for power production, fish and wildlife, and recreational uses. Resources Policy In recent years, consumptive uses of Colorado River water have exceeded natural flows. This causes an imbalance in the basin’s available supplies and competing demands. A drought in the basin dating to 2000 has raised the prospect of water delivery curtailments and decreased hydropower production, among other things. In the future, observers expect that increasing demand for supplies, coupled with the effects of climate change, will further increase the strain on the basin’s limited water supplies. River Management The Law of the River is the commonly used shorthand for the multiple laws, court decisions, and other documents governing Colorado River operations. The foundational document of the Law of the River is the Colorado River Compact of 1922. Pursuant to the compact, the basin states established a framework to apportion the water supplies between the Upper and Lower Basins of the Colorado River, with the dividing line between the two basins at Lee Ferry, AZ (near the Utah border).
    [Show full text]
  • SUPREME COURT of ARIZONA En Banc ) Arizona Supreme Court ) No
    SUPREME COURT OF ARIZONA En Banc ) Arizona Supreme Court ) No. WC-11-0001-IR IN RE GENERAL ADJUDICATION ) OF ALL RIGHTS TO USE WATER IN ) Maricopa County Superior THE GILA RIVER SYSTEM AND SOURCE ) Court Case Nos.: W-1, W-2, ) W-3 and W-4 ) (Consolidated) (Gila) IN RE GENERAL ADJUDICATION ) [Contested Case OF ALL RIGHTS TO USE WATER IN ) No. W1-104] THE LITTLE COLORADO RIVER SYSTEM ) AND SOURCE ) Apache County Superior ) Court Case No. 6417 (LCR) ) [Contested Case ) No. 6417-100] ) ) ) O P I N I O N __________________________________) Review from the Superior Court in Apache County and Maricopa County The Honorable Eddward P. Ballinger, Jr., Judge AFFIRMED ________________________________________________________________ THOMAS C. HORNE, ARIZONA ATTORNEY GENERAL Phoenix By Thomas C. Horne, Attorney General Theresa M. Craig, Assistant Attorney General Attorneys for the State of Arizona THE SPARKS LAW FIRM PC Scottsdale By Joe P. Sparks Laurel A. Herrmann Attorneys for the San Carlos Apache Tribe and Tonto Apache Tribe SALMON LEWIS & WELDON PLC Phoenix By M. Byron Lewis John B. Weldon, Jr. Mark A. McGinnis Attorneys for Salt River Project Agricultural Improvement and Power District and Salt River Valley Water Users’ Association SALMON LEWIS & WELDON PLC Phoenix By Paul R. Orme Attorney for Central Arizona Irrigation and Drainage District and Maricopa-Stanfield Irrigation & Drainage District SNELL & WILMER LLP Phoenix By L. William Staudenmaier, III Andrew M. Jacobs Attorneys for Arizona Public Service Company, Freeport- McMoran Corporation, Roosevelt Water Conservation District POLSINELLI SHUGHART PC Phoenix By Lucas J. Narducci Margaret LaBianca Attorneys for BHP Copper Inc. ENGELMAN BERGER PC Phoenix By William H.
    [Show full text]
  • Quantifying the Base Flow of the Colorado River: Its Importance in Sustaining Perennial Flow in Northern Arizona And
    1 * This paper is under review for publication in Hydrogeology Journal as well as a chapter in my soon to be published 2 master’s thesis. 3 4 Quantifying the base flow of the Colorado River: its importance in sustaining perennial flow in northern Arizona and 5 southern Utah 6 7 Riley K. Swanson1* 8 Abraham E. Springer1 9 David K. Kreamer2 10 Benjamin W. Tobin3 11 Denielle M. Perry1 12 13 1. School of Earth and Sustainability, Northern Arizona University, Flagstaff, AZ 86011, US 14 email: [email protected] 15 2. Department of Geoscience, University of Nevada, Las Vegas, NV 89154, US 16 3. Kentucky Geological Survey, University of Kentucky, Lexington, KY 40506, US 17 *corresponding author 18 19 Abstract 20 Water in the Colorado River is known to be a highly over-allocated resource, yet decision makers fail to consider, in 21 their management efforts, one of the most important contributions to the existing water in the river, groundwater. This 22 failure may result from the contrasting results of base flow studies conducted on the amount of streamflow into the 23 Colorado River sourced from groundwater. Some studies rule out the significance of groundwater contribution, while 24 other studies show groundwater contributing the majority flow to the river. This study uses new and extant 1 25 instrumented data (not indirect methods) to quantify the base flow contribution to surface flow and highlight the 26 overlooked, substantial portion of groundwater. Ten remote sub-basins of the Colorado Plateau in southern Utah and 27 northern Arizona were examined in detail.
    [Show full text]